If you’re scoring at home, the Rangers flipped a 2017 fourth-rounder for a 2018 third-rounder, 24-year-old defenseman Rob O’Gara and 135 games (plus 11 in the playoffs) from Nick Holden following a trade Tuesday that sent No. 55 to the Bruins.

Holden, obtained at the 2016 draft from the Avalanche for that fourth-rounder, is the first Blueshirt out the door in the massive renovation process leading into the Feb. 26 trade deadline that will continue through the summer.

The 30-year-old lefty, who has worked primarily on his off-side for the Rangers, is a depth defenseman best suited for a support, third-pair role. But because of the Blueshirts’ lack of depth, Holden skated on the second tandem most of last year while paired with Marc Staal before moving up to the first unit as Ryan McDonagh’s partner for the last 36 games in which both played this year.

Holden, an impending unrestricted free agent, recorded 46 points (14-32) for the Blueshirts with a relative -1.2 Corsi rating and a plus-10 rating in 19:57 of ice time per game.

O’Gara, a 24-year-old, 6-4, 207-pound lefty, is a native of Massapequa, New York, who attended Yale and was the 151st selection in the 2011 entry draft. O’Gara, who has played 11 career games with the Bruins, has spent most of the last two seasons with AHL Providence.

The addition of the third-rounder gives the Rangers seven picks in the upcoming draft, including all of their own for the first six rounds.